<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
       * {
           margin: 0;
           padding: 0;
       }
       @media screen and (min-width: 320px) {
           html {
               font-size: 50px;
           }
       }
       @media screen and (min-width: 900px) {
           html {
               font-size: 100px;
           }
       }
       .box {
           height: 1rem;
           font-size: 0.5rem;
           text-align: center;
           background-color: pink;
           line-height: 1rem;
       }
    </style>
</head>
<body>
    <div class="box">
        购物车
    </div>
</body>
</html>